A brief description of different processes used in production of fish flour is given, and various studies are reported on the nutritive value of the protein in fish flour prepared by different processes. From the results of the latter, it is evident that at least some procedures do not uniformly result in products of good nutritional value. Considerable variability in nutritional value was observed, due to the use of different extraction procedures. In comparing the therapeutic effects of a maize diet supplemented with 10 % casein (casilan), 10 % South African fish flour or 10 % VioBin fish flour respectively, it was evidenced that neither type of fish flour was as suitable as casein. Better results are reported with isolated soybean protein supplemented with methionine and glycine than with VioBin fish flour on the growing rate of chicks. Little definite information exists on the effects of solvents on the nutritive value of fish protein; there is, therefore, a great need for properly controlled experiments to compare critically the effects of various solvents on the composition and nutritive value of fish flour . From the biochemical point of view, studies should be carried out on the possibility that toxic products may be produced by reactions between fish solids and solvents, solvent decomposition products or solvent impurities. From the technical point of view, studies are needed on the influence of processing variables on the nutritive value of fish flour. At present time, it does not appear possible to state definitely either that any particular process or solvent will always result in a flour of good quality or that any particular process or solvent always yields a poor quality flour. A better understanding of the biochemistry and technology of fish flour is necessary before the material can take its place as an important source of high-quality protein in underdeveloped areas of the world.